Google Checkout Installation

The first step in installing Google Checkout is to simply upload the files to your website - if you are sure there has been no changes to your installation.

There are 2 new files that have to be put into your custom template folder: tpl_gc_return_display.php
tpl_gc_return_noproduct.php

The files that override existing files are:

admin/orders.php

includes/modules/downloads.php

includes/templates/your_templates/
tpl_checkout_payment_default.php
      tpl_login_default.php
      tpl_shopping_cart_default.php
      tpl_time_out_default.php

So the orders.php in admin is the most important file. If you have changed that file already, either do a file compare or follow these instructions to edit orders.php.

Edit downloads.php.

Edit templates.